Power-driven typewriter

ABSTRACT

A power-driven typewriter comprising a shiftable carrier supporting a rotatable and axially movable, flexible type drum having a plurality of type characters therearound. Type keys, when depressed, each condition one each of two groups of actuators and cause operation of a drive member to operate the two conditioned actuators, one of which is effective to rotate the type drum from any position to a new position and the other is effective to raise the type drum to a selected position to thus align a type character corresponding to the key depressed at the printing point. Means are provided to dampen torsional oscillation of the type drum and its drive mechanism prior to printing. Readily interchangeable ink transfer ribbon cassettes for both fabric and for film ribbons are provided. Also, type drums having different type characters or type styles may be readily interchanged.

[ 1 Sept. 9, 1975 Finnegan, Henderson,

ABSTRACT A power-driven typewriter comprising a shiftable carrier supporting a rotatable and axially movable, flexibl of type characters th ressed, each conditi ctuators and cause perate the two condiis effective to rotate to a new position and e type drum to a'setype character corre at the printing point.

Primary ExaminerEdgar Si Burr Assistant Examiner-R. T, Rader Attorney, Agent, or Firm Farabow & Garrett e type drum having a plurality erearound. Type keys, when dep on one each of two groups of a operation of a drive member to o tioned actuators, one of which the type drum from any position the other is effective to raise th lected position to thus align a sponding to the key depressed Ohitomachi, Tagatagun, Shizuoka, Japan Nov. 7, 1972 Appl. No: 304,365

B4lj 33/14 [97/15], I56 I59, 153 R i v tates Patent Temple City. Calif. 91780; Rii Watanabe, 570 Takyo,

References Cited UNITED STATES PATENTS ited Boyden et al.

POWER-DRIVEN TYPEWRITER Inventors: Robert E. Boyden, SO40 Sereno Dr.

Filed:

Int. Cl... Field of SearchmH...

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In the co-pending Robert E. Boyden applications, Ser. No. 773,145, filed on Nov. 4, 1968, and Ser. No. 69,542, filed on Sept. 4, I970, a typewriter of the above type is disclosed and claimed. Although such typewriter is generally satisfactory, problems concerning wear and reliability are encountered in operating the same at relatively high speeds or in cases where two type keys are depressed in very rapid succession. Such problems, generally, arise from inertia and momentum forces developed in rapidly moving the type head and entrained drive mechanism from one type character printing position to another.

SUMMARY OF THE INVENTION In one aspect of the present invention, a rebound preventing device is provided which latches certain of the driving parts for the type drum in advanced positions against the retrograde movement and thus prevents torsional or vibrational oscillation of such parts even though some of the parts are made sufficiently yieldable to absorb the shock incurred in rapidly deaccelerating the type head in a new type character printing position.

In order to further reduce the momentum and inertia forces developed in the typewriter, relatively light and readily interchangeable ink transfer ribbon cassettes or cartridges are provided for supporting the ribbon in endless fashion without accumulating the same on the usual ribbon spools. Such cassettes are arranged to sup port either fabric ink transfer ribbons or plastic film ink transfer ribbons. In order to increase the useful life of such ribbons, each cassette is so actuated that different type characters print on different areas of the ribbon so as to utilize substantially the entire area of the ribbon.

Additionally, certain elements of the shiftable type drum carrier are constructed to perform more than one function to reduce the mass of the carrier and to also reduce the cost of manufacture.

It therefore becomes a principal object of the present invention to reduce inertia and momentum forces, particularly in the drive train for a single element type head.

Another object is to substantially eliminate torsional or vibrational oscillations in the drive train for a single element type head.

Another object is to provide a relatively light ink transfer ribbon mechanism which will accommodate either a fabric ink transfer ribbon or a plastic film transfer ribbon.

Another object is to enable quick and ready interchangeability of different ink transfer ribbons without having to physically touch such ribbons.

Another object is to more fully utilize all areas of an ink transfer ribbon and thus greatly increase the useful life thereof.

Another object is to enable quick and ready interchangeability of a single element print head having a set of type characters thereon.

Another object is to improve the print characteristics of a single element print head having a complete set of type characters thereon.

Another object is to increase the reliability of a single element type head operating mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a longitudinal sectional view through a portion of a typewriter embodying a preferred form of the present invention and illustrating mainly the key responsive device for rotating the type drum.

FIG. 2 is a sectional view illustrating the rebound preventing mechanism.

FIG. 3 is a sectional view of ,a box cam intended to rotate the type drum in a direction opposite to that in which it is rotated by the box cams shown in FIG. 1.

FIG. 4 is a sectional view illustrating mainly the mechanism for raising and lowering the type drum into different positions.

FIG. 5 is a sectional view through the type drum and drum carrier, in which the inking ribbon mechanism is deleted for sake of clarity.

FIG. 6 is a sectional view somewhat similar to FIG. 5 but illustrating the endless fabric inking ribbon mechanism, and is taken substantially along line 66 of Flg. 8.

FIG. 7 is a plan view, partly broken away, of the two piece type drum.

FIG. 8 is a sectional plan view taken substantially along line 8-8 of FIG. 6, illustrating the endless fabric ribbon mechanism.

FIG. 9 is a sectional plan view similar to that of FIG. 8 but illustrating an alternatively usable endless plastic film ribbon mechanism.

FIG. 10 is a sectional view taken along line l0l0 of Flg. 9.

FIG. 11 is a sectional view illustrating the ribbon advancing pawl.

FIG. 12 is a sectional view illustrating the print im-- pression control mechanism.

FIG. 13 is a sectional view illustrating the rotatable platen knob which is capable of being used to alternatively manually rotate the drive motor.

FIG. 14 is a sectional view taken along line l4l4 of FIG. 13.

DETAILED DESCRIPTION OF THE EMBODIMENT Referring to the drawings, the typewriter, in general, comprises a keyboard partly indicated at 11, FIG. 1, which includes 44 depressible type keys forming selecting members, a type drum carrier 12, FIG. 5, shiftable transversely of the typewriter, and a type drum 13 carried by the carrier 12. The drum is rotatably and axially movable to different positions by power under control of different ones of the keys to locate any one of a series of type characters 14, FIGS. 5 and 6, at a printing point P on a nonshiftable platen 15.

As shown in FIGs. 5 to 7, the type drum 13 is formed of two parts 13a and 13b which are molded of a relatively flexible plastic, such as is commercially known as Delrin. In order to make the drum 13 as light as possible and highly flexible in a radial direction but not in an axial direction, the part is constructed in the form of a flexible lattice in which each type character 14 is formed on the outer surface of a radially extending rigid slug 16. Such slugs are interconnected by thin flexible bridging connectors 17, there being interstices 18 intermediate adjacent connectors. The upper end of the part 130 comprises a thin annular wall 20 which terminates in spaced upwardly extending projections 21. The latter are fitted in mating slots formed in a rim 22 forming part of the part 13b. Flexible, substantially inverted U-shaped spokes 23 integrally connect the rim 22 to a thin sleeve 24 which terminates in a realatively rigid hub 25.

The parts 13a and 13b are formed separately to facilitate molding. Thereafter, the projections 21 are fitted within the mating slots in the rim 22 and the parts are integrally united by the use of a suitable adhesive.

The hub 25 of the type drum 13 is slidably keyed for axial movement on a tubular drive shaft 26 which is rotatably mounted on a hollow bearing post 27 attached to the base 28 of the carrier 12. The drive shaft 26 is secured by a threaded nut 30 to the upper end of a shafi 3] which is journalled in the hollow post 27 and is attached at its lower end to a bevel gear 32 meshing with a second bevel gear 33. The latter is slidably keyed on a shaft 34 which is effective to both partly slidably support the carrier 12 and to also rotate the type drum through the gears 32 and 33, to present different type characters to the printing point P. Brackets, one of which is shown at 35, extend from the carrier base 28 on opposite sides of the gear 33 to maintain the gears 32 and 33 in mesh in all positions of the carrier along the platen 15.

The shaft 34 is rotatably mounted in bearings, not shown, carried by the framework of the typewriter and is angularly adjusted to rotate the type drum to different typing positions by a setting shaft 36, FIGS. 1, 2, and 3, through a case shift control mechanism, not shown. Reference may be had to the above mentioned Boyden patent applications Ser. No. 69,542 for a description of such a case shift control mechanism.

Describing now the means for selectively and rotatably positioning the type drum 13 by power under control of the various type keys to present appropriate ones of the type characters thereon in printing position relative to the platen I5, each of the type keys is mounted on a respective lever 37, FIG. I, pivotally supported on a stationary shaft 38 and pivotally supporting an interponent 40 at 41. The latter has a shoulder 42 normally engaging an car 43 on an associated lever 44, which is also independently pivoted on shaft 38.

Each interponent 40 is engaged by a respective leaf spring 45 anchored at 46, which spring urges the interponent clockwise relative to its key lever 37 and thereby also urges the key lever itself clockwise into its illustrated raised position against a suitable stop, not shown.

Each lever 44 has a camming surface 47 on the lower edge thereof which engages an car 48 on an actuator control lever 50 pivotally supported on a stationary shaft 51. The lever 50 is urged clockwise into its illustrated position by a tension spring 52, in which position the lever rests against a part of the typewriter framework. Actuators 54 are also pivoted on the shaft 51 adjacent respective ones of the levers 50 and each is urged clockwise by a tension spring 55 extending between the same and its lever 50 so as to normally maintain a stud 56 thereon in engagement with its lever 50. Each actuator 54 carries an actuator roller 57 located within the opening of a respective box cam 58 keyed to the setting shaft 36.

There are 1 1 actuators 54 and levers 50, one for each group of four keys 11 and levers 44. Thus the four key levers 44 associated with each such group of keys all engage the same car 48 of one of the control levers 50. Accordingly, there are 11 box cams 58 arranged in a helical series partly around the shaft 36 so that when an actuator 54 is rocked upwardly, as will be described later, it can rock such box cam and, therefore, the type drum 13, to an appropriate one of 11 different positions about its axis.

The shaft 36 and the type drum 13 are held in their illustrated central positions by a centralizing device comprising a cam 60, FIG. 1, keyed to the shaft 36 and engagable by the roller 61 of a cam actuator lever 62 fulcrumed at 63 and urged clockwise by a tension spring 64.

Those box earns 58 which are intended to rock the shafi 36 clockwise of its centralized position are constructed as shown in FIG. 1 and, for this purpose, each cam has a camming surface 65 engagable by the respective actuator roller 57 and a pocket 66 into which such roller moves at the upper end of the stroke of its actuator 54. The side 67 of each box cam 58 opposite the camming surface 65 is somewhat flexible so as to yield slightly when the roller 57 moves into the pocket 66 so as to absorb some of the shock incurred in rapidly arresting the box cam and the entrained mechanism, including the type drum 13, when the latter reaches a selected position.

Those box cams 58 which are intended to rock the shaft 36 counterclockwise of its centralized position are constructed as shown in FIG. 3 wherein the camming surface 65 is on the opposite side of its actuator roller 57.

Normally the centralizer lever 62 returns the shafi 36 and type drum 13 to their centralized positions following each typing operation. However, a box cam 580, FIG. 1, similar to the remaining box cams, is provided to be actuated by the respective actuator to return the shaft 36 to such centralized positions in the event a key for selecting such centralized position is depressed prior to return of the shaft from another position.

As disclosed in the above noted Boyden patent application, Ser. No. 773,145, two cyclically operable power clutches are provided, i.e., a space clutch, not shown herein, for character spacing and returning the carrier 12 to an initial position, and an action clutch 70, FIG. 4, for rotating and axially positioning the type drum to locate an appropriate one of the type characters 14 at the printing point P, to cause operation of the space clutch, and to effect printing. For the purpose of advancing the carrier 12, the space clutch drives a worm shaft 69, FIG. 5, which is rotatably supported by the typewriter framework and is threaded through a boss 169 depending from the carrier base 28.

The action clutch 70 is of conventional construction and reference may be had to the above mentioned Boyden application, Ser. No. 773,145 for a description thereof. The latter clutch is controlled by a clutch dog 71 fixed on a rock shaft 72 to which is also fastened an arm 73 pivotally connected by a link 74 to a bail 75 which is pivotally supported by the shaft 38. The bail 75 is held in engagement with the arms of a series of four nested code bails 76, 77, 78 and 80 [see also FIG. I] by a tension spring 79.

Each of the code bails 76 to 80 has spaced tabs 81 thereon extending into engagement of certain of the levers 44.

UPon depression of a type key, its lever 37 will,

through its interponent 40, rock the associated lever 44, camming an associated control lever 50 slightly counterclockwise to likewise rock the respective actuator 54 sufficiently to position a sharp shoulder 82 in front of a power bail 83 which is pivoted at 184 and extends across all of the actuators 54. At the same time, the actuated lever 44 rocks one of the code bails 76 to 80, depending upon which bail has a tab 81 in engagement with such lever, thereby rocking the clutch control bail 75 to cause engagement of the clutch 70. The latter, which is driven by a unidirectional motor '85, FIG. 13, through means not shown, drives a shaft 86 to which is keyed a power bail control cam 87.

A cam follower 88, pivotally supported on a shaft 90, is pivotally connected by a link 91 to the power bail 83 and is held in engagement with the cam 87 by a relatively strong tension spring 84 connected to the bail. When the clutch 70 is engaged, the cam 87 will allow the spring 84 to rock the power bail 83 clockwise, causing it to cam along a curved camming surface 92 on the partially raised actuator 54, thereby forcing the latter further counterclockwise to rock its respective box cam 58 and thus the type drum, into an appropriate new setting.

During rocking of the power bail 83, it will sweep over curved surfaces 94 on the remaining actuators 54, preventing such actuators from being raised at this time by their associated keys. Later, toward the end of the cycle, the cam 87 will return the power bail 83 to its illustrated home position, permitting a new key to be depressed to select the next type character.

In addition to the interlocking feature comprising the power bail 83 for preventing concurrent operation of two or more actuators 54, a ball type interlock device, generally indicated at 95, is provided to prevent simultaneous depression of two different keys. such device comprises a series of balls 96 movable along a channel shaped track 97 extending across the various actuators 54. The balls 96 are spaced to permit only one of such control lever 50, at a time, to be inserted between two of the balls 96.

Upon depression of a key and consequent slight counterclockwise rocking of the associated control lever 50, a shoulder 98 on the latter will rock into its dot-dash line position 98a where it extends up to substantially the mid-diameter of two adjacent balls 96 where it will be arrested, although the actuator 54 will continue upwardly through its power stroke. Upon subsequent return of the actuator 54, the studs 56 will strike its lever 50 and thus impel the same downwardly, aided by spring 52, to insure removal of the locking shoulder 98 from between two adjacent balls 96 even though the operator should, at this time, be pressing down on a new key.

During high speed operations, of which the typewriter of the present invention is capable, torsional oscillations tend to be set up in the box cams 58 and shaft 36 due to the extremely rapid arresting of a box cam 58 by its actuator 54 as an actuator roller 57 enters a pocket 66 in such box cam. In order to reduce or eliminate such oscillations, so as to aid in bringing the type drum to rest prior to printing, a rebound preventing device generally indicated at 100, FIG. 2, is provided.

Such device comprises an arm 101 keyed on the setting shaft 36 and provided with two sets or ratchet teeth 102 and 103 thereon. The teeth 102 and 103 are cooperable with respective pawls 104 and 105 fulcrumed at 106 and 107, respectively, and both urged toward the arm 101 by a spring 108 tensioned between both pawls. Pawl 104 has a camming shoulder 110 thereon which extends in the path of the power bail 83.

Normally, when the typewriter is at rest, the bail 83 engages the cam shoulder 110, as depicted in FIG. 2, to maintain a pawling tooth 111 thereon out of engagement with the arm 101. Pawl 104 engages an ear 112 on pawl 105 to likewise maintain a pawling tooth 113 on pawl 105 out of engagement with the arm 101.

At the start of a cycle, and as the power bail 83 moves clockwise past the camming shoulder 110, spring 108 causes both pawls 104 and 105 to engage an arcuate section 109 on the forward edge of the arm 101 intermediate the sets of teeth 102 and 103. Now, as the shafi 36 is rocked in one direction or the other from its central position, one or the other sets of teeth 102 and 103 will ratchet under an associated pawl tooth 111 or 113. As an operated actuator roller 57 moves into the pocket 66 of a selected box cam 58 and the portion 67 of the cam yields slightly, the pawl tooth will locate behind one of the ratchet teeth, thus locking the arm 101, and consequently the shaft 36, from retracting. Toward the end of the cycle, and after the printing operation to be described subsequently is completed, the power bail 83 will again engage the camming surface 110 to retract the pawls 104 and 105 into their illustrated positions, permitting centralizer spring 64 to return the shaft 36 and thus the type drum 13 to their centralized positions.

Means are provided under control of the different type keys to differentially raise the type drum into any of four positions to align appropriate ones of the circumferentially arranged rows of type characters 14 with the printing point P concurrently with rotation of the type drum so as to directly align a type character corresponding to a depressed type key with such point. For this purpose, a set of four actuator control levers 50a, FlG. 4, similar to levers 50, are independently pivoted on the shaft 51 adjacent respective actuators 54a, similar to actuators 54. Such actuators 54a are likewise pivotally supported by the shaft 51 and carry cam follower rollers 57a which cooperate with box cams 58b, similar to cams 58, and all arranged in a helical series on a setting shaft 115 which is independent of, but c0- axial with, the setting shaft 36. Suitable bearings, not shown, support the shaft 115 for rocking movement independently of shaft 36.

Attached to shaft 115 is an arm 116 pivotally connected by a link 1 17 to an arm 118 attached to the shaft 90 [see also FIGS. 5 and 6]. The latter shaft, along with shaft 34, slidably supports the type drum carrier 12 for movement along the platen 15. A yoke 120 is slidably keyed to the shaft 90 and is located between brackets 121 on the carrier 12 so as to move along with the carrier. The arms 119 of the yoke 120 are slotted at 109 to embrace trunnion pins 122 carried by a ring 123 seated within a groove in the hub 25 of the type drum 13. The ring 123 also carries a stud 124 which is guided in a vertical slot 129 formed in an equalizing post 125 fixed to the base 28 of the carrier so as to prevent rotation of the ring 123 about the axis of the type drum 13. The function of the equalizing post is described in the above noted Boyden patent application Ser. 69,542.

In order to enable the last typed character or characters to be viewed by the operator, the type drum 13 is normally held in its lower position illustrated in FIG. 5 wherein the upper row of type characters 14 lies below the level of the printing point P. For this purpose. the lever 116, and accordingly the shaft 90, are held in their extreme clockwise rocked positions by a tension spring 100, in which position the lever 116 limits against a suitable stop 131.

Each of the code bails 76 to 80, FIGS. 1 and 4, carries a camming foot 133 which engages an ear 48a on a respective one of the actuator control levers 50a. Accordingly, when a type key is depressed, and, as noted heretofore, one of the code bails 76 to 80, and one only, depending on the location of the tabs 81, will be actuated to rock an associated lever 50a likewise rock its associated actuator 54a a short distance, placing its camming surface 920 in the path of the power bail 83. Thus, the actuator will be operated in the same manner as described in connection with the actuators 54 to engage its box cam 58b and thus, through shaft 115, appropriately position the type drum 13 into a selected axial position while it is also being rotated.

It will be noted that the power bail 83 is effective to sweep over curved surfaces 94a of those actuators 54a which have not been set by their keys to prevent concurrent setting of two or more of the actuators 54a in the path of the power bail 83.

The ball type interlock comprising locking balls 96, FIG. 1, is preferably extended in a manner not shown to also control the actuator control levers 50a.

Means are provided under control of the action clutch 70 to imprint a selected type character 14 opposite the printing point P onto a sheet of record material supported around the platen l5 shortly after the type drum 13 has been properly positioned. For this purpose, a shaft 149, FIGS. 5 and 12, is rotatably mounted at its ends in bearings carried by the typewriter framework and has slidably keyed thereon a combined printing hammer and centralizer arm 236. The latter is lo cated between two brackets 139, carried by the base 28 of the carrier 12 so as to constrain the arm to move with the carrier. The arm 236 has an indented head portion 237 adapted to engage a pyramidal formation 238 on a generally aligned one of the type slugs 16 to accurately center the aligned type character 14 just prior to printing.

The shaft 149 is driven by the action clutch 70. FIG. 4, to cause an imprint through an impression control mechanism shown in FIG. 12. For this purpose, a pair of cams 136 and 137, carried by a shaft 135, are driven through a complete revolution during each cycle of the clutch 70 by means not shown. The cam 136 has a dwell portion 138 normally engaged by a roller 140 carried by a bail 141 fixed on the shaft 149 and urged against the cam 136 by a tension spring 142 whereby it normally holds the printing arm 236 in its position shown in FIG. 5.

At a mid-portion of a cycle of clutch 70, the cam 136 allows the spring 142 to rock the shaft 149 counterclockwise, causing the arm 236 to frictionally engage the sleeve portion 24 of the type drum 13 to dampen any torsional oscillations of the type drum occasioned by the abrupt arresting of the same. Shortly thereafter, the cam 137 engages a roller 143 on an arm 144 pivoted on shaft 149 and carrying a roller 145 which engages a wedging member 146. Member 146 is pivoted at 147 to a manually settable control member 148 pivotally supported at 150 and suitably maintained in different adjusted positions. The wedging member 146 also engages a roller 151 on the bail 141. Thus, the wedging member 146 transmits a clockwise rocking motion to the bail 141 to swing the printing arm 236 out of engagement with the sleeve portion 24 of the type drum 13 and into engagement with a generally aligned type slug 16, causing a radial flexing of the type drum 13 and a tilting thereof about the spokes 23 to effect printing.

By adjusting the manually settable member 148 about its pivot 150 the wedging member 146 may be positioned to change the angular relationship between the bail 141 and the arm 144 to correspondingly adjust the amount of printing impression in accordance, for example, with the number of carbon copies to be printed or the desired intensity of the print. However, in order to obtain a clear printing impression in all cases, a relatively heavy weight 153 of lead or the like is attached to the upper end of the bail 141. Thus, the bail 141 acts as a hammer to sharply drive the printing arm 236 against an aligned type slug 16. Due to the tor sional resiliency of the portion of the shaft 149 extend ing between the arm 236 and the bail 141. the weight 153 tends to rebound sharply, thus withdrawing the arm 236 immediately after printing to prevent smudging, phantom printing or the like.

An indicating pointer 154, FIGS. 5, 6 and 8 is pro vided to indicate the position of the type drum l3, and therefore, the printing point P, along the length of the platen 15. Such pointer also enables ready release of the type drum 13 to permit removal or replacement. For this purpose, the pointer 154 is formed integrally with a bail portion 155 having trunnion pins 156 journaled in bearings formed in the brackets 12] of the carrier 12.

A flexible depending projection 157 on the pointer 154 is normally detented in a notch 158 in one of the brackets 121 to hold the pointer in its lower most position, shown in full lines in FIG. 5, wherein the pointer extends in cooperative relation with a stationary indica tor scale 160, FIG. 8, having indicia 159 thereon for indicating the location of the printing point. Also, when the pointer 154 is in its lower position its bail portion 155 forms a block to arrest a shoulder 161 on the yoke 120 to prevent counterclockwise rocking of the yoke beyond its upper dot-dash line position 1200 shown in FIG. 5 wherein the lower most row of type characters 14 on the type drum are located in line with the print ing point P. It will be noted that in this position of the yoke 120, the slots 109 therein will still embrace the trunnion pins 122 and thus prevent removal of the type drum from the post 26. However, upon rocking of the pointer 154 into its upper dot-dash line position 154a, its bail 155 will permit further counterclockwise movement of the yoke 120 whereby the type drum 13 may be grasped and completely withdrawn from the post 26. Thus, the type drum 13 may be readily replaced by other type drums having different type characters or different style type characters thereon.

Provision is made to readily use and interchange both fabric inked printing ribbons or plastic inked film printing ribbons. For this purpose, such ribbons are provided in endless loop form on readily removable and replaceable cassettes or cartridges. One such cassette, generally indicated at 180, FIGS. 6 and 8, contains an endless fabric inking ribbon 181 and the other cassette, generally indicated at 182, FIGS. 9 and 10, contains an endless plastic film inking ribbon 183. A principal feature of the ink ribbon system is that cassettes of either type may be readily interchanged without having to touch the ribbon.

Describing first the fabric ribbon type cassette 180, the latter comprises a hollow plastic body 184 having a pair of trunnion pins 185 and 186 removably journaled in bearings 187 and 188, respectively, formed on the aforementioned carrier brackets 121.

Rubber feed rolls 190 and 191 are rotatably mounted on studs 192 extending upwardly from the bottom of the cassette 180 to engage and feed the ribbon 181 lengthwise. For this purpose, a ratchet wheel 193 is attached to the roller 191 and, when the cassette is in place, the ratchet wheel is engageable by the upper end of a pawl 194, see also FIG. 11, which extends upwardly through an opening 196 in the bottom wall of the cassette and is pivotally supported at 197 on the type drum carrier 12. The pawl 194 is normally urged clockwise by a tension spring 198 into engagement with a part of the base 28. During rocking movement of the power bail 183 as described heretofore, a portion 201 thereon engages the lower end of the pawl 194, causing the same to advance the ratchet wheel 193 to incrementally advance the ribbon 181.

The cassette body 184 includes a semicircular wall 202 terminating in two rearwardly extending ribbon guide walls 203 and 204 which partly surround the type drum 13.

The ribbon 181 is drawn around the guide wall 203, across the rear of the type drum 13, around the guide wall 204 and between the rollers 190 and 191, from whence it accumulates into a series of random loops. The ribbon is guided past an ink saturated pad 205 lucated within a cavity 206 formed in the body 184 whereby to reink the ribbon as it approaches the printing point and also to exert a slight drag on the ribbon so that the ribbon stand 181a extending between the guide walls 203 and 204 will be maintained taut.

A second ink saturated pad 207 is contained within a cavity 208 formed in the body 184 and is arranged in wiping contact with the roller 190, the latter being effective to transmit a film of ink onto the ribbon as the latter passes between the rollers 190 and 191.

Means are provided to normally maintain the cassette 180 in a clockwise rocked position about the pivot pins 185 and 186, as seen in F IG. 6, to locate the strand 181a of the ribbon below the printing point P and in its full line position shown in FIG. 5 so as to enable the last printed character or characters to be visible to the operator. Such means is also effective to raise the cassette 180 to locate the ribbon opposite the printing point P, as indicated by the dot-dash lines 181b, FIG. 5, during the printing operation. Such means is further effective to differentially rock the cassette 180 slightly and by different amounts when printing different type characters so that substantially all parts of the ribbon are effectively used to transmit printing imprint, thereby greatly extending the useful life of the ribbon. For this purpose, each of the yoke arms 119, FIG. 6, is provided with an inwardly projecting stud 210 on which camming surfaces 211 on the cassette normally rest.

When the shaft is rocked counterclockwise to raise the type drum 13 to locate any of the rows of type characters 14 in alignment with the printing point P, the studs 210 move along the camming surfaces 211 to raise the cassette about the pivot pins and 186 until the studs engage curved cam ways 212 thereby loeating the rear strand 1810 of the ribbon generally opposite the printing point P. However, as the shaft 90 is rocked by different amounts to locate the different circumferential rows of type characters opposite the printing point, the studs 210 move to different positions along the cam ways 212 to additionally adjust the cassette and ribbon strand 181a slightly different amounts between the limits indicated by dot-dash lines 180a and 1801; in FIG. 6. Accordingly, different areas of the ribbon are used to transfer imprints of the type character, thereby more completely utilizing the full area of the ribbon and increasing the life thereof.

When the type drum 13 is lowered after a printing operation, the studs 210 withdraw from the cam ways 212, allowing the cassette 180 to drop under the influence of gravity to its full line position shown in FIG. 6.

When it is desired to remove the cassette 180 from the typewriter, a flexible extension 199 supporting the pivot pin 186 is pressed laterally, removing the pin 186 from its bearing 188, whereupon the cassette may be readily removed for replacement.

Describing now the plastic ink ribbon cassette 182, FIGS. 9 and 10, the latter comprises a'body 220 on which are mounted spaced trunnion pins 221 and 222. The pin 222 is carried by a flexible section 223 whereby the latter may be sprung to permit mounting and removal in the bearings 187 and 188, FIG. 8, in the same manner as the pins 185 and 186 of the cassette 184.

Ribbon feed roller 224 and 225 are rotatably mounted on studs 226 extending from the bottom of the cassette body and a ratchet wheel 227, similar to ratchet wheel 193, is secured to the roller 224 and is adapted to be advanced by the pawl 194 whereby to incrementally advance the ribbon 183.

The cassette body 220 has a semicircular wall 228 and rearwardly extending ribbon guide walls 230 and 231 for supporting a rear strand 1830 of the ribbon intermediate the type drum l3 and platen 15. Also, the cassette body is provided with camming surfaces and slots, not shown, similar to the surfaces 211 and slots 212 of FIG. 6 to enable the cassette 182 to be rocked in the same manner as is the cassette 180.

After passing between the feed rollers 224 and 225 the ribbon 183 is accumulated onto the outer periphery of a ribbon roll 233 which is supported by a flanged spool 234 rotatably mounted on a stud 235 extending upwardly from the cassette body 220.

A cover 236 is fitted over the stud 23S and is provided with a slot 237 to guide the ribbon onto the roll 233 and a second inclined slot 238 to guide the ribbon from the inside periphery of the roll, in a twisting movement onto the guide wall 230 during which the ribbon twists I80". Due to such twist in the ribbon extending between the roll 234 and the guide wall 230, the surface of the film exposed to the platen 15 is reversed after each passage of the film through the cassette so that both sides of the ribbon may be coated with ink and eventually transferred to the record material.

Referring to FIGS. 13 and 14, the platen 15 is secured to a platen shaft 240. The latter is journaled in bearings, one of which is shown at 245 supported by a carriage side plate 246 forming part of the typewriter framework and extends outwardly through an enlarged opening 241 in a typewriter housing 242.

A platen knob 244 having a hollow hub 243 thereon is slidably fitted over the shaft 240 and is keyed thereto by tongues 247 which slidably fit in key ways 248 formed in the shaft 240, thus enabling manual rotation of the platen in either direction.

The platen knob 244 is also capable of rotating the motor 85 in its intended direction only, as may be desired when servicing the typewriter or if the motor should stall for any reason. For this purpose, the motor 85 is provided with a motor shaft 250 having a diameter substantially equal to the distance across oppositely located tongues 247.

When it is desired to manually rotate the motor, the knob 244 is removed from the platen shaft 240 and slidably mounted on the motor shaft 250. In this case, inclined triangular teeth 251 on the end of the platen knob hub 243 engage similar inclined teeth 252 on the end of a sleeve 253 attached to the motor shaft. In the event the motor 85 should be energized while the knob 244 is being held in place, the inclined surfaces of the teeth 251 will cam the mating teeth on the knob outwardly to avoid injury to the operator.

I claim:

1. A typewriter comprising a carrier,

means supporting said carrier for movement along a record medium, a single element printing head having a plurality of rows of type characters thereon spaced apart in a first direction,

head guide means on said carrier guiding said head for movement in said first direction,

head moving means for moving said head in said first direction to different positions to align different ones of said rows of type characters at a printing point,

ribbon mounting means supported by said carrier for receiving an ink transfer ribbon,

ribbon positioning means responsive to said head moving means for moving said ribbon in said first direction to different ink transferring positions relative to said printing point, said ribbon positioning means including first means on said head moving means and second means on said ribbon mounting means operatively engaging said first means to effect a different particular ink transfer position corresponding to each particular head position in which one of said rows of type characters is aligned with said printing point, and

means for imprinting an aligned type character onto said record medium.

2. A typewriter according to claim 1 comprising ribbon guide means for guiding said ribbon past said printing point and intermediate said head and said record medium,

means for advancing said ribbon endwise over said ribbon guide means, and

wherein said first means is camming means and said second means is cam following means.

3. A typewriter according to claim 1 wherein said ribbon mounting means comprises a ribbon guide for guiding said ribbon past said printing point, means for advancing said ribbon endwise over said ribbon guide, pivot means for pivotally supporting said ribbon guide on said carrier to enable movement of said ribbon to said ink transferring positions,

said pivot means being movable to facilitate removal of said ribbon guide from said carrier.

4. A typewriter according to claim 1 comprising a ribbon guide for guiding said ribbon past said printing point, means for advancing said ribbon endwise over said ribbon guide, spaced aligned bearings on one of said carrier and said ribbon guide, spaced pivots carried by the other of said carrier and said ribbon guide and journalled in said bearings,

one of said pivots being movable endwise relative b the other to enable removal of said ribbon guide from said carrier.

5. A typewriter comprising a. a carrier,

b. means supporting said carrier for movement along a record medium,

c. a single element printing head having a plurality of axially and circumferentially spaced type characters thereon,

d. support means on said carrier for movably supporting said head,

e. head moving means for axially moving said head to align different ones of said type characters at a printing point,

f. an ink transfer ribbon,

g. a cassette on which said ribbon is mounted, said cassette including a ribbon guide for guiding said ribbon endwise past said printing point, ribbon moving means for advancing said ribbon endwise,

means for pivotally mounting said cassette on said carrier, and

ribbon positioning means on said ribbon guide operably movable by means on said head moving means for pivoting said ribbon guide from a position locating said ribbon below the said printing point to different particular ink transferring positions locating said ribbon in alignment with said printing point, each ink transferring position corresponding to a particular axial head position.

6. A typewriter according to claim 1 wherein said head moving means includes an arm supported for pivotal movement about an axis, said arm operatively engaging said head at a position spaced from said axis and means for effecting pivotal movement of said arm,

said first means is a stud projecting from said arm spaced from said axis, and

said second means is a camming surface on said ribbon mounting means which is in engagement with said stud whereby pivotal movement of said arm effects moving said head and said ribbon in said first direction in direct correspondence.

7. A typewriter according to claim 6 wherein said ribbon is an endless ribbon and said ribbon guide means includes means for twisting said ribbon l during said endwise advancement thereof.

8. A typewriter commprising a carrier,

a platen,

means supporting said carrier for movement along the platen,

a single element printing head having a plurality of rows of type characters thereon spaced apart in a first direction,

head moving means for selectively moving said head to align selected ones of said rows of type characters at a printing point,

ribbon support means,

an ink transfer ribbon on said support means for movement along the platen,

ribbon positioning means, said head moving means having first means which engages means on said ribbon positioning means for moving said ribbon to different ink transferring positions relative to said printing point, each ink transferring position corresponding to the position of the head, and

means for effecting impact of a selected type character on said ribbon.

9. A typewriter as defined in claim 8 wherein said ribbon positioning means includes a cam surface on said ribbon support means and wherein said first means is cam operating means on said head moving means acting against said cam surface.

10. A typewriter as defined in claim 8 wherein said head moving means includes an arm supported for pivotal movement about an axis, said arm operatively engaging said head at a position spaced from said axis and wherein said ribbon positioning means includes a cam surface on said ribbon support means, cam operating means on said arm spaced from said axis and acting against said cam surface, and means for effecting pivotal movement of said arm effecting moving said head to selected positions and movement of said ribbon to corresponding ink transferring positions.

11. A typewriter as defined in claim 9 wherein said ribbon is housed within a cassette and said cam surface is on said cassette.

12. A typewriter as defined in claim 8 wherein said ribbon support means includes a ribbon guide for guiding said ribbon past said printing point, pivot means for pivotally supporting said ribbon guide on said carrier spaced from said platen and wherein said ribbon position means includes a cam surface on said ribbon guide and cam operating means on said head moving means acting against said cam surface.

13. A typewriter as defined in claim 12 wherein said pivot means includes spaced aligned bearings on one of said carrier and said ribbon guide and spaced pivots on the other of said carrier and said ribbon guide and journalled in said bearings and wherein at least one of the pivots and bearings is movable relative to the carrier to enable removal of said ribbon guide from the carrier. il k 

1. A typewriter comprising a carrier, means supporting said carrier for movement along a record medium, a single element printing head having a plurality of rows of type characters thereon spaced apart in a first direction, head guide means on said carrier guiding said head for movement in said first direction, head moving means for moving said head in said first direction to different positions to align different ones of said rows of type characters at a printing point, ribbon mounting means supported by said carrier for receiving an ink transfer ribbon, ribbon positioning means responsive to said head moving means for moving said ribbon in said first direction to different ink transferring positions relative to said printing point, said ribbon positioning means including first means on said head moving means and second means on said ribbon mounting means operatively engaging said first means to effect a different particular ink transfer position corresponding to each particular head position in which one of said rows of type characters is aligned with said printing point, and means for imprinting an aligned type character onto said record medium.
 2. A typewriter according to claim 1 comprising ribbon guide means for guiding said ribbon past said printing point and intermediate said head and said record medium, means for advancing said ribbon endwise over said ribbon guide means, and wherein said first means is camming means and said second means is cam following means.
 3. A typewriter according to claim 1 wherein said ribbon mounting means comprises a ribbon guide for guiding said ribbon past said printing point, means for advancing said ribbon endwise over said ribbon guide, pivot means for pivotally supporting said ribbon guide on said carrier to enable movement of said ribbon to said ink transferring positions, said pivot means being movable to facilitate removal of said ribbon guide from said carrier.
 4. A typewriter according to claim 1 comprising a ribbon guide for guiding said ribbon past said printing point, means for advancing said ribbon endwise over said ribbon guide, spaced aligned bearings on one of said carrier and said ribbon guide, spaced pivots carried by the other of said carrier and said ribbon guide and journalled in said bearings, one of said pivots being movable endwise relative to the other to enable removal of said ribbon guide from said carrier.
 5. A typewriter comprising a. a carrier, b. means supporting said carrier for movement along a record medium, c. a single element printing head having a plurality of axially and circumferentially spaced type characters thEreon, d. support means on said carrier for movably supporting said head, e. head moving means for axially moving said head to align different ones of said type characters at a printing point, f. an ink transfer ribbon, g. a cassette on which said ribbon is mounted, said cassette including a ribbon guide for guiding said ribbon endwise past said printing point, ribbon moving means for advancing said ribbon endwise, means for pivotally mounting said cassette on said carrier, and ribbon positioning means on said ribbon guide operably movable by means on said head moving means for pivoting said ribbon guide from a position locating said ribbon below the said printing point to different particular ink transferring positions locating said ribbon in alignment with said printing point, each ink transferring position corresponding to a particular axial head position.
 6. A typewriter according to claim 1 wherein said head moving means includes an arm supported for pivotal movement about an axis, said arm operatively engaging said head at a position spaced from said axis and means for effecting pivotal movement of said arm, said first means is a stud projecting from said arm spaced from said axis, and said second means is a camming surface on said ribbon mounting means which is in engagement with said stud whereby pivotal movement of said arm effects moving said head and said ribbon in said first direction in direct correspondence.
 7. A typewriter according to claim 6 wherein said ribbon is an endless ribbon and said ribbon guide means includes means for twisting said ribbon 180* during said endwise advancement thereof.
 8. A typewriter commprising a carrier, a platen, means supporting said carrier for movement along the platen, a single element printing head having a plurality of rows of type characters thereon spaced apart in a first direction, head moving means for selectively moving said head to align selected ones of said rows of type characters at a printing point, ribbon support means, an ink transfer ribbon on said support means for movement along the platen, ribbon positioning means, said head moving means having first means which engages means on said ribbon positioning means for moving said ribbon to different ink transferring positions relative to said printing point, each ink transferring position corresponding to the position of the head, and means for effecting impact of a selected type character on said ribbon.
 9. A typewriter as defined in claim 8 wherein said ribbon positioning means includes a cam surface on said ribbon support means and wherein said first means is cam operating means on said head moving means acting against said cam surface.
 10. A typewriter as defined in claim 8 wherein said head moving means includes an arm supported for pivotal movement about an axis, said arm operatively engaging said head at a position spaced from said axis and wherein said ribbon positioning means includes a cam surface on said ribbon support means, cam operating means on said arm spaced from said axis and acting against said cam surface, and means for effecting pivotal movement of said arm effecting moving said head to selected positions and movement of said ribbon to corresponding ink transferring positions.
 11. A typewriter as defined in claim 9 wherein said ribbon is housed within a cassette and said cam surface is on said cassette.
 12. A typewriter as defined in claim 8 wherein said ribbon support means includes a ribbon guide for guiding said ribbon past said printing point, pivot means for pivotally supporting said ribbon guide on said carrier spaced from said platen and wherein said ribbon position means includes a cam surface on said ribbon guide and cam operating means on said head moving means acting against said cam surface.
 13. A typewriter as defined in claim 12 wherein said pivot means includes spaced aligned bearings on one of said carrier and said ribbon guide and spaced pivots on the other of said carrier and said ribbon guide and journalled in said bearings and wherein at least one of the pivots and bearings is movable relative to the carrier to enable removal of said ribbon guide from the carrier. 